The Trouble with Jumbo

On the apron outside Boeing's plant in Everett, Wash., 15 enormous 747 jets stand high and silent, harbingers of a new era in aviation. They are painted in the colors of several international airlines: TWA, Pan Am, Lufthansa, Air France. For the moment, however, the planes are the world's largest gliders --because they have no engines. Pan Am had been scheduled to get the first three commercial giants, each with a capacity of 362 passengers, in late November. Last week embarrassed Boeing officials said that performance difficulties in the Pratt & Whitney JT9D engines would delay that delivery by as much as eight weeks.

Lost Edge. Pan Am postponed indefinitely its plans for an inaugural flight to London on Dec. 15. At Boeing, officials promised that once the engine problem is solved, deliveries of the planes will be accelerated in order to catch lip quickly with the original schedule. Thus Pan Am, which had hoped to have its 747s in service more than a month before competitors, will probably lose some of that advantage. The airline now does not expect to begin scheduled flights until late January. TWA, which had planned to fly passengers in its giant jets in early 1970, should be only slightly affected by the delay.

The problem is that Boeing had originally asked Pratt & Whitney to provide an engine thrust of 41,500 Ibs. As the weight of the plane rose during development, however, the engineers had to revise this figure to 43,500 Ibs.--all within the original production schedule. When the engine strains for that much power, its casing tends to distort or "ovalize." That, in turn, reduces the amount of thrust and raises fuel consumption by 5%. Pratt & Whitney engineers are trying to find a way of installing stiffening rods that would eliminate distortion of the casing. The Federal Aviation Administration will have to approve any engine change.

Money Needed. The giant jets face other obstacles. Few major airports are equipped to handle the massive passenger flow that the new planes will bring. Yet by the end of next year, the 747s are expected to be flying to cities across the U.S. and in Europe. Some nightmarish tangles could lie ahead. Airports will need billions of dollars in the next few years to improve and enlarge terminal facilities alone, and nobody knows where the funds will come from. The prospect of raising the money has been made even more difficult by congressional proposals to limit the tax-free status of municipal bonds.

Last week the transportation committee of the Wayne County board of supervisors recommended a ban on jumbo jets at Detroit's Metro Airport. To expand the ramp, terminal and baggage facilities, it was predicted, would cost an estimated $6,000,000--and there is simply no money available.

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